This treatment outcome study will examine the combined efficacy of a systems/structural approach to family therapy, designed specifically for the families of substance abusing adolescents, and a "Chemical Dependency, Plus" (CDP) model of treatment. The research will specifically address whether the addition of systems family therapy will enhance the outcomes achieved with CDP. CDP is a model similar to that used at many psychiatric treatment facilities for adolescents which combines substance abuse counseling with treatment for co-morbid psychiatric conditions. Family Therapy for Chemical Dependency in Adolescence (FTCDA) addresses family risk and protective factors in substance abuse. 112 eleven to eighteen year old adolescents will be referred to an existing established Chemical Dependency Program located within the Child Guidance Clinic (CGC) of Duke University's Division of Child & Adolescent Psychiatry. Consecutive referrals will be randomly assigned to receive the existing CDP model or to CDP + FTCDA. The CDP program is administered by professional staff at the CGC. FTCDA will be administered by Master's level therapists hired and trained for this project. Outcome measures will include parent and child structured psychiatric interviews for ascertaining psychiatric diagnosis, substance abuse, family dysfunction, and social impairment; reliable and valid behavior problem checklists, and other measures of family and emotional dysfunction. Therapy process measures also will be collected. Analyses will test the hypotheses that the addition of family therapy to the more common treatment approach (CDP) significantly enhances the outcomes achieved in treatment, and significantly retards relapse at 6 month follow up. In addition, hypotheses regarding variables predicting good vs. poor outcome will be tested.